Cost-effectiveness of letrozole versus tamoxifen as initial adjuvant therapy in postmenopausal women with hormone-receptor positive early breast cancer from a Canadian perspective

Abstract

Background

In the primary core analysis of BIG 1–98, a randomized, double-blind trial comparing 5 years of initial adjuvant therapy with letrozole versus tamoxifen in postmenopausal women with hormone receptor-positive (HR+) early breast cancer, letrozole significantly improved disease-free survival by 19% and reduced the risk of breast cancer recurrence by 28% and distant recurrence by 27%.

Methods

A Markov model was used to estimate the incremental cost per quality-adjusted life year (QALY) gained with 5 years of initial adjuvant therapy with letrozole versus tamoxifen from a Canadian healthcare system perspective. Probabilities of recurrence and side effects for tamoxifen were based on published results of BIG 1–98 and other published population-based studies. Corresponding probabilities for letrozole were calculated by multiplying probabilities for tamoxifen by estimated relative risks for letrozole versus tamoxifen from BIG 1–98. Other probabilities, costs of breast-cancer care and treatment of side effects, and health-state utilities were obtained from published studies. Costs and QALYs were estimated over the lifetime of a cohort of postmenopausal women with HR+ early breast cancer, aged 60 years at initiation of therapy, and discounted at 5% annually.

Howell A, on behalf of the ATAC Trialists’ Group (2004) The ATAC (‘Arimidex’, Tamoxifen, Alone or in Combination) trial in postmenopausal women with early breast cancer—updated efficacy results based on a median follow-up of 5 years. Abstract No. 1, San Antonio Breast Cancer Symposium

Locker GY, on behalf of the ATAC Trialists’ Group (2004) Cost-utility analysis of anastrozole versus tamoxifen as primary adjuvant therapy in postmenopausal women with early breast cancer from a US healthcare system perspective: the 5-year completed treatment analysis of the ATAC (‘Arimidex’, Tamoxifen Alone or in Combination) trial. 27th Annual San Antonio Breast Cancer Symposium, December 8–11, 2004. Abstract 2085

Laupacis A, Feeny D, Detsky AS, Tugwell PX (1992) How attractive does a new technology have to be to warrant adoption and utilization? Tentative guidelines for using clinical and economic evaluations. Can Med Assoc J 146:473–481